More big mammals found in high-carbon forests, says new study

The researchers used satellite data to measure forest carbon values and camera trap photographs to tally the mammal species present in forests and oil palm plantations.

Finer-scale data did reveal that high-carbon areas do support more species of medium and large mammals that are threatened with extinction.

Experts say that this research validates the high carbon stock approach for identifying priority areas for conservation.

Still, further research is required to better understand the role of connectivity between high-carbon forests in supporting biodiversity.

Carbon-rich tropical forests, which are often among the least-disturbed habitats, seem to be ideal bastions for sensitive and threatened animals, particularly compared to lower-carbon areas like timber and oil palm plantations.

But until recently, data-driven conclusions connecting high levels of both carbon and biodiversity have been elusive.

“Scientists have been trying to link carbon with biodiversity for a number of years, but with variable success,” said Nicolas Deere, an ecologist at the Durrell Institute of Conservation and Ecology at the University of Kent in the United Kingdom, in an interview.

Recent research by Deere and his colleagues revealed that high-carbon tropical forests do support more biodiversity than those with less carbon, bolstering the case for the use of carbon assessments to identify forests important for conservation on a number of fronts. The team published their findings Nov. 6 in the Journal of Applied Ecology.

The team chose the patchwork of forests and plantations that make up the Stability of Altered Forest Ecosystems, or SAFE, project area in southern Sabah, in Malaysian Borneo. Critical to demonstrating the relationship between carbon and biodiversity levels was the researchers’ use of high-resolution satellite data to pinpoint areas with the most carbon. They also used camera traps to record the number of species present in different habitats.

Previous studies have often looked at coarser data sets, in which the carbon values for larger areas might represent a range of different forest qualities. In places like Sabah, where humans have altered huge parts of the landscape, a relatively pristine remnant of forest might be adjacent to farms or oil palm plantations. When averaged over a large area, Deere said, “The carbon value of that fragment is going to be dragged down by the agricultural areas around it.”

Similarly, studies looking at biodiversity on broader scales than the data that’s collected with camera trapping often miss the nuanced impacts that forest quality can have on the diversity of species in an area. For example, the presence of animals that can survive in oil palm plantations might give the mistaken impression that an area still supports a wide range of species. In reality, these “disturbance-tolerant generalist species … obscure the trend,” he said.

Deere and his team paired both high- and low-resolution carbon data with camera trap captures from both forests and oil palm plantations. While the low-resolution data didn’t bear out a relationship, the finer-scale data did reveal that high-carbon areas support more species of medium and large mammals threatened with extinction.

Grant Rosoman, a global forests solutions senior adviser with Greenpeace, who was not an author of the paper, said that the findings support the use of HCS — short for “high-carbon stock” — assessments. This tool can help identify areas for conservation under certification schemes such as those currently being considered for inclusion in the criteria set by the Roundtable on Sustainable Palm Oil.

“This is highly significant because it means that identifying forest via the HCS Approach or similar assessments to achieve no deforestation is at the same time protecting biodiversity,” Rosoman said in an email. “This will have a big impact on being able to quickly and efficiently identify tropical forest areas that are priority for both biodiversity and carbon protection.”

H added that the proven linkage between carbon and biodiversity could bump up the value of carbon-rich forests for these “biodiversity co-benefits” under payment-for-ecosystem programs such as REDD+. REDD+ stands for “reducing emissions from deforestation and forest degradation,” and it aims to compensate developing countries for maintaining standing forests within their borders.

A sun bear (Helarctos malayanus) at the Bornean Sun Bear Conservation Centre in Sabah. Photo by John C. Cannon/Mongabay.

At the same time, Rosoman said unanswered questions remain about “the impact of HCS forest patch shape, connectivity and configuration in the landscape on biodiversity.”

In other words, how does biodiversity respond to habitats that are increasingly split up into smaller pieces by human activity?

“I can’t emphasize the fragmentation caveat enough” with the current study, Deere said.

“We’ve provided the first validation of the HCS approach,” he said. Now, he added, further research is necessary to look into how landscape fragmentation impacts biodiversity and what’s required for “an ecologically functional forest network in these plantation landscapes.”